Homann, M;
Sansjofre, P;
Van Zuilen, M;
Heubeck, C;
Gong, J;
Killingsworth, B;
Foster, IS;
... Lalonde, SV; + view all
(2018)
Microbial life and biogeochemical cycling on land 3,220 million years ago.
Nature Geoscience
, 11
pp. 665-671.
10.1038/s41561-018-0190-9.
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Abstract
The colonization of emergent continental landmass by microbial life was an evolutionary step of paramount importance in Earth history. Here we report direct fossil evidence for life on land 3,220 million years ago (Ma) in the form of terrestrial microbial mats draping fluvial conglomerates and gravelly sandstones of the Moodies Group, South Africa. Combined field, petrographic, carbon isotope and Raman spectroscopic analyses confirm the synsedimentary origin and biogenicity of these unique fossil mats as well as their fluvial habitat. The carbon isotope compositions of organic matter (δ13Corg) from these mats define a narrow range centred on −21‰, in contrast to fossil mats of marine origin from nearby tidal deposits that show δ13Corg values as low as −34‰. Bulk nitrogen isotope compositions (2 < δ15N < 5‰) are also significantly different from their marine counterparts (0 < δ15N < 3‰), which we interpret as reflecting denitrification in the terrestrial habitat, possibly of an atmospheric source of nitrate. Our results support the antiquity of a thriving terrestrial biosphere during the Palaeoarchaean and suggest that a complex and microbially driven redox landscape existed during the deposition of the Moodies Group, with distinct biogeochemical cycling occurring on land by 3,220 Ma.
| Type: | Article |
|---|---|
| Title: | Microbial life and biogeochemical cycling on land 3,220 million years ago |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1038/s41561-018-0190-9 |
| Publisher version: | https://doi.org/10.1038/s41561-018-0190-9 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Biogeochemistry, Carbon cycle, Palaeoecology, Precambrian geology, Sedimentology |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10087311 |
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